In 1958 Schutz introduced a theory of interpersonal relations he called Fundamental Interpersonal Relations Orientation (FIRO). According to the theory three dimensions of interpersonal relations were deemed to be necessary and sufficient to explain most human interaction. The dimensions are: Inclusion, Control and Affection. These dimensions have been used to assess group dynamics.

Schutz also created FIRO-B, a measurement instrument with scales that assess the behavioral aspects of the three dimensions. A survey of seventy-five of the most widely used training instruments, including the MBTI, completed in 1976 by Pfeiffer and Heslin, found that "the FIRO-B was the most generally usable instrument in training." The popularity of the FIRO-B has been eclipsed by the MBTI as the latter became widely used in business. In recent years, however, interest in FIRO has picked up. It has even been instrumental in the development of a relatively new theory of Five Temperaments.

In the countries of the former USSR FIRO-B became known only in the first decade of 2000s, but it is still surpassed in popularity by socionics, a post-Jungian theory of compatibility in interpersonal relationships.